Rotary mowers for mowing shallow angle furrows are constructed with two pivotally connected cutting wings. The rotary cutters carried by the wings are driven from the power take-off of a towing tractor. In order to mow a complete furrow, including sides and bottom, the cutters cut swaths that overlap at the bottom. This requires the two cutters to be synchronized with their blades in a 90.degree. out of phase relationship. This relationship must be maintained at all times in order to avoid damage to the cutters. Synchronization of the rotary cutters on a machine in which the wings must fold can result in a less than ideal drive line arrangement, which in turn may result in undesirable fluctuations in cutter speed. In addition, where one of the cutters is halted by engaging a foreign object, the complete drive train must be halted producing very high shock loadings in the drive system.
The present invention is concerned with a novel rotary mower for shallow furrows in which these problems are eliminated or ameliorated.